matlab求点云平均距离

下面是我的代码，但总提示维度不一致，望大神指点一二，非常感谢啦
function ave_dpoint=ave_dispoint(p)
k=8;
p_Mdl=KDTreeSearcher(transpose(p));
p_neighbors = transpose(knnsearch(p_Mdl, transpose(p), 'k', k+1));
m=size(p,2);
for i=1:m
x = p(:,p_neighbors(2:end, i));
y=sqrt((p(:,i)-x(:,i)).^2);
end
ave_dpoint=mean(y);
end